It was at 60 psi for a while and I droped it to 44psi and the car ran like crap, lean. So I upped it to 54 and it runs better. But I need to figure out why it needs to be set so high.

I use a 0-100 pressure transducer as my sensor in the AFPR and log/display it on an AiM data logger. I am considering getting an analog gauge and run it in the rail to see if the sensor pressure tranducer is bad. Usually when the pressure tranducers fail they read negative and I don't have this issue.

 

gotcha yep that makes sense. for sure dude check it out and report back, im curious lol. im using an analog gauge setup and it hasnt failed me.

 

I am sure it leaned out because the car was tuned at that fuel pressure. Oh, any tips on relieving the presure from the rail or is it just slowly removing one of my aN lines?

 

why would your IDC's change?

 

I have no idea. All I know is that when the car was tuned the FP was at 60psi on the stock pump. I have always thought this was way to high. So I dropped it to 43 and the car would never get below 13.5 AFR. After seeing and feeling this I raised the pressure 10 psi and would now see AFR's in the low 12's high 11's. As a side note the car is very responsive to running on the lean side, more power. I know that this is trouble so I upped the FP to about 57 and that seems to be good for now.

Clipse3GT is coming down to tune my car next week along with a few others so hopefully we will get this all worked out.

 

well it was a mistake to tune the car with a 60psi base pressure... especially on the stock pump.

of course if you change the rail pressure the AFR's will also change. IDC's/IPW will stay the same...

I would put it back to 60psi until it can be retuned, TELL THE NEW TUNER THE STORY so far...

 

I know. I raised the pressure back this morning. I did like how the car was on the edge of lean though...

The tuner was the prior owner and before I owned the car he had a larger turbo and an inline 044 pump. So it was set up for that. Funny thing is I asked him to look at the FP and he said it was fine. I don't know why he did not want to change it. Lazy I guess.

Clipse3GT knows the whole story. One of the reasons I am having him come down instead of an e-tune is so he can look at and drive the car. It is modified and since I have never owned a stock GSR I have no idea what stock configurations look like.

 

Well running the base pressure higher will make the entire tune richer up until the fuel pump runs out of flow. The biggest problem is that fuel pumps flow less LPH as pressure increases so at 60 psi base +25 psi boost, the rising rate FPR has the pump at 85 psi which puts the stock pump way down on LPH flow rate. There have been reports that the return line into the stock fuel pump assembly clogs up with debris and artifically raises fuel pressure. By upgrading pumps you likely corrected that problem and things returned to normal.



I should put the stock pump onto this chart I made but the Walbro is only 10-20% better overall. Results published around the web will vary since unless you perform all the tests with the exact same testing equipment, you will get some variance. It's not exact but gives a rough idea of what is happening as pressure increases: flow must decrease. The stock pump falls off the worst compared to these upgrades so it's no surprise people have issues with them if something in the fuel return lines causes an increase in pressure.

 

Nice bit of data. Once I have the car re-tuned next week we will set the base pressure back down to 43.

 

I put a lot more faith in my stock pump than I should have....and I now have a built motor...if you have anything but basic basic basic bolt-ons, upgrade the pump. Cheap insurance.

 

Interesting claim that MRT of Australia explains about upgrading your stock fuel pump. google "evo x fuel pump problems".

 

is this it?

http://www.youtube.com/watch?v=2BO8sl1_vrE

 

yes that's it, you are fast!

 

I know this is an old thread but I found it very helpful so I thought I would add for future reference. I also found that when it was hot outside & the fuel heated up my car knocked a lot more.

Only mods at the time were intake, HFC, UICP and a Baka tune. For whatever reason my pump was definitely weak and could not keep up with the new fuel demand.

So I replaced my pump with the DW65c and it fixed all my problems.
Now I also never let the car go below 1/3 tank to keep the pump cool, DW65c was the best $150 I've spent on the car.